1. Field of the Invention
The present invention relates to an apparatus for dispensing individually predetermined lengths of a web material, such as textile materials, wallpaper and the like from a roll of wound web material.
2. Description of Background Art
When dispensing lengths of such web material in retail vending operations it is quite time-consuming to manually release the required length of web material from the roll, manually measure the length required and manually sever the length from the roll. Furthermore, the accuracy of the manual measuring and severing depends on the particular person performing these operations. Apart from the quite large variations in accuracy because of individually varying degrees of care, skill and concentration, the manual process itself is quite inaccurate, particularly when the lengths involved require a plurality of repeated measuring operations, and even more so when the roll is unwieldy. Because of these inaccuracies, and the requirement inherent in the use of such web materials that the length should not be shorter than requested by the customer, it is necessary to systematically dispense lengths longer than requested. This factor, together with unavoidable mistakes in manual severing and measuring causing wastage represent a considerable loss, particularly when the web materials involved are costly.
Commonly, the web materials in question are stocked wound into rolls with a central core, such as bolts of cloth, fabric and the like. Such rolls, particularly bolts of cloth or fabric, may depart substantially from a circular cylindrical shape, for instance having a rectangular cross-section with rounded corners. To achieve the automatic release of web material from such uncircular cylindrical rolls special unwinding means must be employed.
An apparatus of the type mentioned above is known from U.S. Pat. No. 4,004,748 which discloses unwinding conveying means comprising an unwinding cradle for a bolt of fabric having an oblong cross-section, said cradle being constituted by a loop of an endless driven belt supported by and depending from two guides that are relatively movable towards and away from each other as the bolt rotates, the guides moving relatively away from each other as the bolt rotates to a horizontal position and toward each other as the bolt rotates away from the horizontal position. The frequency of the cyclical widening and narrowing of the unwinding cradle in relation to the conveying speed of the endless belt sets limits for the variation of the cross-sectional dimensions of the bolts to be unwound which does not allow all common bolt sizes to be dealt with. Furthermore, when the web material is to be unwound from the bolt, the leading end and a considerable adjacent length of web material must be unrolled and placed correctly over the downstream guide to ensure correct unwinding. This is difficult, particularly for inexperienced customers in a retail operation, and the weight of some bolts will practically render this operation impossible for persons with slight physical strength.